1. Field of the Invention
The invention relates to a system for the administration of medicaments into extracorporeal circuits. In particular, the invention relates to an adapter which makes possible the direct connection of a standard injection vial to an extracorporeal circuit, avoiding the introduction of air into the circuit.
2. Description of the Related Art
Continuous extracorporeal circuits are used in medicine mostly for a treatment of the blood outside the patient's body. In particular in haemodialysis, blood is removed from the patient in a continuous process, the removed blood is purified by means of a dialyser and is returned immediately to the patient's blood circulation. The patient's blood is conveyed here by means of at least one pump. It usually circulates in an extracorporeal tube set which contains and connects with each other means for arterial removal, sections for conveying blood by insertion into the blood pump, connections for the dialyser, a venous drip chamber, means for the venous return of the blood to the patient and a venous drip chamber. As an alternative to such a tube set, cassette systems are also used, in which at least parts of the conduit pathways, connections and the drip chamber are integrated in an injection- or blow-moulded plastic cassette. However, the fundamental conduit pathways also remain contained in a cassette system.
The clinical picture of patients treated by means of extracorporeal circuits mostly requires the intravenous administration of medicaments. Usual medicaments for the treatment of dialysis patients comprise, for example, vitamin D and recombinant erythropoietin and iron preparations for the treatment of anaemia.
Such medicaments are usually provided in injection vials. An administration takes place by the hospital personnel, by the corresponding dose of the medicament being transferred into a disposable syringe and being administered via injection sites provided for this in the extracorporeal tube set or cassette set. In this way, the medicaments can be administered in a time-saving manner during the extracorporeal treatment and without the necessity of an additional connection of the patient for infusion.
The injection sites are mostly designed here as T-pieces which are accessible through a septum or through a Luer connector which is able to be closed off. A disadvantage of the administration through such access points is the use of an additional disposable part, the syringe, for the transfer of the medicament. Furthermore, the administration via a syringe equipped with a cannula harbours a risk of injury for the hospital personnel and a problem connected therewith in the waste management of the disposable syringes. Most medicaments are administered here as a bolus. However, there are also medicaments, such as the iron preparation Venofer for example, which are preferably administered over a longer period of time. In such a case, the manual injection is time-consuming, because the hospital personnel must be available for this task over the entire time period of the extended injection.
A similar problem to the addition of medicaments is also posed in the addition of anticoagulating agents. Outside the body, the blood tends to coagulation. Although the biocompatibility of tube- and cassette sets and of dialysers is being constantly improved, the coagulation of the blood can not be prevented without the addition of anticoagulating agents. The addition of anticoagulating agents, such as heparin or citrate, takes place in the dialysis treatment likewise via the extracorporeal circuit and preferably not as a bolus, over a certain period of time. For this purpose, most dialysis machines contain a device for the infusion of the anticoagulating agent, mostly heparin. Such heparin pumps are usually constructed as injection pumps which are automatically controlled.
DE 38 37 298 discloses the arrangement of a heparin-filled injection in the underpressure region of the extracorporeal circuit and a passive suction of the heparin into the extracorporeal circuit.
U.S. Pat. No. 5,330,425 and EP 966 631 disclose tube sets with a blow-moulded venous drip chamber with various injection sites for medicaments on the drip chamber and in the tube set behind the drip chamber.
U.S. Pat. No. 4,500,309 discloses the infusion of citrate solution into the arterial region of the extracorporeal circuit and the infusion of calcium solution into the venous region of the extracorporeal circuit.
EP 532 432 discloses the infusion of a substitute solution into the extracorporeal circuit. WO 87/07159 discloses a double-lumen transfer piece for the connection of an injection vial.